So here is the scenario: an adult male 80kg, 6ft tall, slim build free falls into the open ocean feet first, hands locked into the groin. Speed at entry can be 200km/hr. We can assume the water is perfectly stile in reference to the surface tension. and for the body we can estimate some factors and numbers.. lets assume the body is prolate spheriod - completely rigid. not taking into account limbs flailing on impact and effecting ones drag on decent. Following entry the water trajectory during descent can be assumed in direct line with gravity. ones bouyancy can be assumed neutral or slightly negative. lung capactiy of 5.5 litres. My first question is at to what approximate depth would one calculate the body to penetrate the surface? (until the body has deaccelerated to a motion where the bouyancy is the only force relation) yes you could use specific dynamic modelling software, if anyone knows any good software let me know. I would like to see some estimated calculations first. If I have not stated any important information in my model please use a general value and state it in the reply. thanks Andy.